This invention relates in general to a split shaft transfer case for selectively connecting a source of rotational power to a rotatably driven mechanism in a drive train system. In particular, this invention relates to an improved structure for such a split shaft transfer case that facilitates the installation and use of one or more power take-offs.
Drive train systems are widely used for generating rotational power from a source and for transferring such rotational power from the source to a rotatably driven mechanism. For example, in most land vehicles in use today, an engine/transmission assembly generates rotational power, and such rotational power is transferred from the engine/transmission assembly through a driveshaft assembly to an axle assembly so as to rotatably drive the wheels of the vehicle. In some of such land vehicles, a split shaft transfer case is provided in the drive train system for selectively connecting the engine/transmission assembly to the axle assembly for intermittent operation. When the split shaft transfer case is engaged, the engine/transmission assembly is connected to (and, therefore, rotatably drives) the axle assembly and the wheels of the vehicle. When the split shaft transfer case is disengaged, the engine/transmission assembly is disconnected from (and, therefore, does not rotatably drive) the axle assembly and the wheels of the vehicle.
Split shaft transfer cases are frequently provided on trucks and other specialty application vehicles having one or more accessories provided thereon that perform desired functions. Generally, the split shaft transfer case is engaged when it is desired to move the vehicle from one location to another and disengaged when it is desired to stop the vehicle and operate the accessories at a particular location. For example, a concrete pumping truck may be provided with a variety of linear and rotary actuators for mixing and dispensing concrete. The split shaft transfer case is initially engaged to move the concrete pumping truck to a desired location. Then, the split shaft transfer case is disengaged to operate the linear and rotary actuators to mix and dispense the concrete without moving the concrete pumping truck from that desired location.
In many instances, the accessories that are provided on the vehicle (such as, for example, the linear and rotary actuators that may be provided on the above-described concrete pumping truck) are operated when supplied with pressurized hydraulic or pneumatic fluid. In order to supply such pressurized hydraulic or pneumatic fluid to the accessories, it is known to provide one or more hydraulic or pneumatic pumps on the vehicle. The pumps selectively supply pressurized fluid to the accessories when operation thereof is desired. To accomplish this, one or more power take-offs may be provided on a portion of the drive train system. Power take-offs are well known mechanical devices that are, for example, commonly connected to sources of rotational power (such as engines, transmissions, and split shaft transfer cases in a drive train system) to selectively provide mechanical rotational power to rotatably driven accessories. Thus, in a drive train system that includes a split shaft transfer case, it is known to connect one or more power take-offs on the split shaft transfer case to selectively operate accessories that are provided on the vehicle.
Although power take-offs have been used effectively in conjunction with split shaft transfer cases in the past, it has been found that in some instances, it is relatively difficult and time consuming to install the power take-off assemblies on the split shaft transfer cases. Such installation difficulties can be caused by a limited amount of physical space between the split shaft transfer case and other components of the vehicle, such as the side rails of the vehicle frame. Such installation difficulties can also be caused by a lack of axial alignment between an output structure of the power take-off and an input structure of the rotatably drive accessory. Thus, it would be desirable to provide an improved structure for a split shaft transfer case that facilitates the installation and use of one or more power take-offs.